In the packaging of fluid products in commercial size container such as five gallon pails, a need has arisen for a fast pouring, tamperproof closure possessing a high degree of sealing efficiency on molded plastic containers. One such prior art closure consists of a threaded plug with a separate tamperproof overseal. This arrangement while satisfying to some degree the functional requirements, is at the same time seriously lacking in cost effectiveness. Not only are the separate plug and overseal components relatively costly items, in addition, molding the internally threaded container neck is expensive as is the application of the two separate closure components after the container if filled.
Also failing to meet the basic functional requirements has been the use of well known nestable spout type closures. While such pouring spout closures are easily crimped onto a simple opening neck, they cannot offer the quick emptying capacity desired. These closure arrangements only encourage the end user to, in one way or another, destroy the closure to achieve faster pouring, a practice fraught with hazard.
Frequently lacking in the prior art crimped on closure arrangements is the degree of sealing integrity needed to meet current packaging regulations. This deficiency becomes particularly apparent over the wide range of dimensional and surface variations encountered on mass produced plastic container openings. Adequate sealing strength to overcome these variations under extreme performance conditions is not always supplied by the prior art crimped on closures.